Electrical circuit with modulating or rectifying devices



Nov. 30, 1937. H. WALTER 2,100,458

ELECTRICAL CIRCUIT WITH MODULATING OR RECTIFYING DEVICES Filed May 18,1934 C a i I i g I i I d l I E INVENTOR HA/VS W417i? BY g M ATTORNEYPatented Nov. 30, 1937 i V I r UNITED T -S PATENT PFFW ELECTRICALCIRCUIT MTIICMODUIKTING V on. RECTIFYING DEVICES Hans Walter,Berlin-Siemensstadt, Germany, as signer to Siemens & Halske,Aktiengesellschaft, Siemensstadt, near Berlin, {Germany a corporation ofGermany 1 Application May 18, 1934', Serial N6,- 7263 Q In Germany May18,1933 1 Claims. 7 (Cl. 250-21) v r 7 This' invention relates toelectrical cir- The corresponding relation between the resultcuits whichinclude modulating or rectifying 'deing currenti and tl re voltage u -isgiven day the vices. Itisapparent that distortionless modulaexpression rv tion or rectification would result, if a rectilinear 5 relationbetween input current and output volt- V 7 age existed in' the modulatoror rectifier. From Equations 1) and 2 and t well Such an ideal conditionhas never been produced k n l w o :Kifghhofl the mcints p 5; in knownmodulating or rectifying circuits. are Seen to be i I Moreover,departing from this relation in the L operation of vacuum or gas filledtubes, aswell (3 1q= "(Gp.-i qa) V ,1

as in rectifiers of the dry cell type,such as copper .l V V y oxiderectifiers in circuits known heretofore proi ib v .1. duces distortingharmonics in the output of the G rectifier or modulator. V 1 G l 252 51' 7 A One object of the invention is to increase the (5) -(E ipo-weroutput without increasing distortion. -Anv V other-object is todecrease distortion Without de- GG+GP+.*-1Sthevcqnductancebetweenlhe 7creasing power'output. 'Still anotherobject is to mifi gg g gggfigg fzgg igg' fi Y approach an ideal modulating or rectifying device. theresulting conductance; G is so djmensiohed j laresent s isb-asledfllfthe that the Equation (2) contains no terms or third ow e'ge: 'In mo ula ing or. rec i ying' circui s i I combined withresistances in parallel or series mm -m t o the expressmn arrangementthe ccefiicientofthe third harmonic V 4 g of" the equation giving therelation between the (6) 7d instantaneous values of applied voltage'andre- 25 a a It is-to beseen that suitable dimensioning-of 811117111current in b re resented b an e uav tion h aving l ositiiie arid negative terr n s. In 'acthe resigances combined with rectifier the:cofdance with the present invention it isproposed dlstomon occun'mg fmm.t m to overcome the disadvantages of the known may f d q ea gioryelmnnated. By corremodulatingor rectifying devicesby' such adispondmggdlfnensmflmg @180 the Q E t 3 3omensioning of'the resistancescombined with the n e f t utstead of'the 'thlrdharmomcs' modulator'orrectifier, that the coefficient of the T1115 deneilslon 5 lmpfortam? fordetect9r third orhigher harmonicsis zero. meiaurmg p 1. Whlchvthe h aThe invention mayrnow e more fully under monies do not generate directcurrentand are stood by reference to the following description,therefore Q e I when .read inconnection with the accompanying TheEquatwn (6) canals) bgsatlsfied wlthout drawing, Figure .1 of whichillustrates an :electhe P e the riara'uel't'eslstance is' i tricalrectifying circuit and Figure 2 of whichposslbleitqsatlsfithlsiequatlonfinlylbyesultable: shows a curve of .aknow'n rectifying device of the dimension of the resistance combined inS i 40 dry cell type such as copper. oxide. v h f n modulating grePtifyiPg device" 40' In Figure 1 R0 isarectifier with thealternatomlttimg; e? 9 3 9? combined w h ing current resistance R0. Therectifier R0 in the rectifier G follows for h '5 j series with aresistance of the conductance Gv is conductancerthe'expresslon connectedwith a source of electromotive force, I

the voltage of which is u. A resistance of the V e conductance G isconnected in parallel with the TbereforefromEqu-atlon the'relaitmnrectifier. The voltage across the parallel resistdamensioqofltherconductancefif the Senes ance is designated with us. 'Therelation between slstances y the equation- 77 r the current id and thevoltage as is determined 52 by :physical .qualitiesof'the rectifier andmaybe t=- d g 59 v expressed by theequation 1 2 3 The characteristic ofa rectifier device 'with dry (1) cells (comprising e. g. ametallicqnemberjsuch (a 6 7,; are coefficients, characterizing the as acopper-or iron plate having a coating ofgea 55 qualtities of therectifier.) V V compound such'as anoxide of themetalformed 55' idirectly thereon) can be given approximately by the followingexponential function:

(Cr represents the rectifying constant of the rectifier, R0 representsthe algebraic sum of the .By inserting these three coemcients inEquation (7) we get the expression as the characteristic equation forthe elimination of the third harmonics.

According to the invention the resistance combined in series withthemodulating or rectifying devices is so chosen, that its value is thehalf of the alternating current resistance of the rectifier ormodulator. V

The resistance being so dimensioned the power output can be increased.The increasing of the power output is restricted by the generating offourth harmonics of inadmissible value. Practically the inventionpermits increase of the power outputwhile distortion is held within thesame value as is usual in circuits not dimensioned according to the,present invention. The invention permits the distortion to be diminishedif the power output is maintained at the same value as in circuits notarranged in accordance with the present invention.

The derivation of the equations referred to above was made withoutconsidering the capacity of the modulating or rectifying device. Above acertain frequency this capacity varies the resulting equations.

The capacitance of the rectifier ought tobe con sidered, if it cannot beneglected compared with the alternating current resistance R0. Accordingto another idea of the present invention the influenceof the rectifiercapacity is decreased to such. a small degree that it may be neglected.For this purpose the alternating current resistance R0 of. themodulating or rectifying device is decreased by a suitable biasingpotential from a source B connected as shown. The usual choke coil D maybe included in the biasing circuit to prevent the alternating currentfrom reaching the biasing source. This automatically causes the uppercut-off frequency of the rectifier to increase. Figure 2 shows therelation between the current i and the voltage e of a copper oxiderectifier of normal construction. The slope of this curve for a certainvoltage is proportional to the reciprocal of the resistance R0 for thisvoltage. It is apparent that at the point B of the curve the currentvaries in a greater degree when voltage varies than at the point A. ItWill be seen, that the alternating current resistance R0 of themodulating or rectifying devices decreases substantially by increasingof the biasing potential.

'pendance has a large value.

By moving the point on the resistance in series with B and changing thebiasing potential of the rectifier the upper cut-off frequency of thecircuit can be adjusted to the value required.

Another object of the present invention is to compensate for thedependence on temperature of the alternating current resistance. It isknown, that for copper oxide rectifiers this de- The alternating currentresistance change amounts to 40 per cent (when temperature increases10%). According to the invention the biasing potential is always soregulated that the alternating current of the rectifier always has thesame suitable value.

The regulating of the rectifier or modulator resistance in accordancewith the invention is not restricted to the compensation for undesiredbine a suitable number of rectifiers in parallel.

Compared with this method the present invention causes a substantialreducing of means. In the scope of the invention it is possible, toregulate automaticaly the biasing potential with means well known tothose skilled in the art.

It will be obvious that the general principles herein disclosed may beembodied in many other forms different from those illustrated, withoutdeparting from the spirit of the invention as defined in the followingclaims.

What is claimed is:

1. In an electrical circuit, a rectifying device, a resistance in serieswith said device, means for applying alternating current wave energy tosaid device and resistance, and a second resistance in parallel withsaid device, said resistances being so dimensioned that the conductanceof the resistance in parallel with said rectifying device is practicallynull with respect to the applied alternating current and the conductanceGv of the resistance connected in series with said rectifying devicewith respect to said applied alternating current is determined by theexpression wherein d [3.1, 7. denote the coefiicients of thecurrent-voltage id, ud characteristic a= aa+I dd +'Yaa'+ of therectifying device.

2. In an electrical circuit, a translating device having a substantiallyexponential voltage ampere characteristic, means for applyingalternating current wave energy thereto, a resistance in series withsaid device, said resistance having a conductance 1 wherein we. Ba, 1.;denote the coefiicient of the current-voltage 1'4, u characteristic ofthe translating device.

3. An electrical circuit as recited in claim 2 in The known method;

which said translating device is a rectifier of the copper oxide type.

4. An electrical circuit as recited in claim 2 in which an adjustablesource of potential is connected in shunt with said translating device,whereby the ratio between the resistance of the translating device andthe capacity of the translating device may be adjusted when thefrequency of the applied alternating current is changed.

5. In an electrical circuit, a rectifying device, a resistance in serieswith said device, means for applying alternating current wave energy tosaid rectifying device and resistance, and a second resistance having avalue such that wherein Old, Ba, 74, denote the coefficients of thecurrent voltage i id characteristic 1 i a=ada+I dd +'Yaa of therectifying device.

HANS WALTER.

